The conventional brown-out detection circuits (BOD) are comparatively simple, the working principle of which is shown in FIG. 1: when the power supply voltage Vcc operates normally, the output Bout of BOD is the high level. When the power supply voltage Vcc is lower than a certain threshold Vth, Bout is changed to the low level immediately.
However, the conventional BOD is very sensitive to noise of the power supply voltage and interference, especially when the threshold Vth and the power supply voltage Vcc have a little difference and noise and interference cause Vcc to be lower than the threshold Vth, even if the duration of noise and interference is very short, Bout will also become to be the low level, so that the anti-noise ability and the anti-interference ability of the system will be weak.